onion

noun

on·​ion ˈən-yən 

plural onions

1

: a widely cultivated Asian herbaceous plant (Allium cepa) of the amaryllis family that has a pungent edible bulb and that is closely related to the garlic, chive, and leek

also : its bulb

2

: any of various usually ornamental alliums (such as Allium amplectens or A. caeruleum) related to the onion

oniony

ˈən-yə-nē 

adjective

an oniony flavor

oniony meatloaf

Examples of onion in a Sentence

The recipe calls for chopped onions.

He is growing onions in the garden this year.

The recipe calls for chopped onion.

Recent Examples on the Web

Start with the Single Smash, layered with griddled onions, American cheese, lettuce, tomato, pickles, and smash sauce, then explore variations from there, including a falafel smash for vegetarians. — Kaila Yu, Forbes.com, 30 June 2026

The dog can also be served in a classic Chicago-style, topped with mustard, relish, onion, tomato, celery salt, sport peppers and pickle. — Hannah Hudnall, USA Today, 29 June 2026

Keep potatoes away from direct sunlight, and don't store them near onions or fruits like bananas, which release Ethylene gas that increases ripening. — Aly Walansky, Southern Living, 29 June 2026

Pour vinegar mixture over onion mixture and let sit for at least 30 minutes. — ABC News, 29 June 2026

Word History

Etymology

Middle English, from Anglo-French oignon, from Latin union-, unio

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing onion

• Bermuda onion
• green onion
• onion dome
• onion ring
• pearl onion
• sea onion
• Spanish onion
• spring onion

Rhymes for onion

• trunnion

Kids Definition

onion

noun

on·​ion ˈən-yən 

: a widely grown Asian herb related to the lilies and having edible bulbs that have a sharp odor and taste and are used as a vegetable and to season foods

also : its bulb